Gaskets are often used as a layer of material placed between contact surfaces or parts needing a sealed joint. Gaskets are commonly employed to prevent the escape of gas or leakage between two contact surfaces that are bolted together, a task that is difficult to accomplish in high-temperature, high-pressure environments, such as that of an internal combustion engine. A common application involves the placement of a metallic gasket between a cylinder head and an exhaust manifold. Another application involves gasket placement between the exhaust manifold and an exhaust pipe flange. Gaskets for either application are considered high temperature gaskets, and more particularly exhaust manifold gaskets, since the gaskets provide an exhaust seal that is intended to prevent the byproducts of combustion exiting the engine from escaping into the engine compartment of a vehicle.
Because exhaust from an engine is extremely hot, heat shields are commonly incorporated into the exhaust system to protect other underhood components from excessive temperature and to help protect people from burns and other injuries that could result from physical contact with the system. In general, such heat shields are formed from a corrosion-resistant metal, such as aluminized steel, which is die-formed to conform generally to the shape of a manifold while providing air space between the components. In some instances, a multi-layer heat shield may be used to further improve the heat resistance and to provide a sound damping effect.
Such manifold-type gaskets are typically installed by positioning the gasket between a first mating component, such as a cylinder head, and a second mating component, such as an exhaust manifold. Apertures formed in the gasket are then aligned with the corresponding apertures formed in the mating components. Commonly, a threaded fastener is then passed through the select apertures of the first mating component and gasket to engage a corresponding threaded aperture formed in the second mating component. A heat shield is then usually incorporated into the assembly and secured in a conventional manner.
In a number of known assemblies, a heat shield is attached to various components, such as engine components, using a plurality of separate fasteners, tabs and spacers. In other applications, the heat shield is attached to a component, such as a cylinder block, with a sealing material. However, both of those methods necessarily involve the use of additional fastening components and/or sealing materials that can often be lost or dislodged, causing misalignment and less secure assemblies. Furthermore, such conventional heat shield assembly methods often involve more complicated and time-consuming positioning and assembly procedures.
Based upon such limitations, there exists a need in the industry for an improved gasket that provides support for a heat shield assembly in an efficient, reliable and economic manner.